The present invention relates to methods for making semiconductor devices, in particular, semiconductor devices that include high-k gate dielectric layers.
MOS field-effect transistors with very thin silicon dioxide based gate dielectrics (including those consisting of a silicon dioxide/silicon oxynitride film stack) may experience unacceptable gate leakage currents. Forming the gate dielectric from certain high-k dielectric materials, instead of silicon dioxide, can reduce gate leakage. It may be difficult, however, to integrate such high-k dielectric materials with polysiliconxe2x80x94the preferred material for making the device""s gate electrode.
Accordingly, there is a need for an improved process for making a semiconductor device that includes a high-k gate dielectric. There is a need for such a process that enables a polysilicon-based gate electrode to be formed on such a gate dielectric to create a functional device. The method of the present invention provides such a process.